Nephroptosis: Kidney Prolapse, Causes and Treatment

Renal prolapse, also known as nephroptosis, is a condition in which the kidney shifts excessively downward when the body becomes upright, typically by more than 5 cm or the height of two vertebrae. When lying down, the kidney returns to its normal anatomical level. In most people, this displacement is harmless and asymptomatic, but in some patients, it causes pain, urinary obstruction, and recurrent urinary tract infections. [1]

Young, thin women are most often affected, primarily affecting the right kidney. Symptoms, when present, often depend on posture: pain intensifies when standing and decreases when lying down. The clinical significance of nephroptosis remains debated, but accumulated data demonstrate that in appropriately selected patients, documented displacement with functional impairment can cause pain and hydronephrosis. [2]

Modern diagnostics rely on imaging in two positions—lying and standing—which allows for the detection of not only anatomical shifts but also functional changes, such as decreased renal perfusion, ureteral kinking, or delayed emptying of the renal pelvis. This is important because standard studies performed only in the supine position often appear "normal." [3]

Treatment is individualized. For mild, uncomplicated cases, non-drug measures are sufficient. In cases of persistent pain, documented obstruction while standing, recurrent infections, or decreased function, surgical fixation of the kidney (nephropexy) is considered, primarily through laparoscopic access with a high chance of pain relief. [4]

Code according to ICD-10 and ICD-11

The International Classification of Diseases, Tenth Revision, Clinical Modification, provides a separate code for nephroptosis, N28.83 "Nephroptosis." In some national versions of the Tenth Revision, nephroptosis may be listed under N28.8 "Other specified diseases of the kidney and ureter," but the current Clinical Modification uses a separate entry. [5]

In the International Classification of Diseases, Eleventh Revision, nephroptosis is coded GB90.0 "Nephroptosis" and is included in the "Certain Specified Diseases of the Kidney or Ureteral" section. The Eleventh Revision allows for the addition of clarifying codes, if necessary, to detail the affected side and associated conditions. [6]

Table 1. ICD codes

Classification	Code	Name
ICD-10-CM	N28.83	Nephroptosis
ICD-10 (some versions)	N28.8	Other specified diseases of the kidney and ureter
ICD-11	GB90.0	Nephroptosis
[7]

Epidemiology

Nephroptosis is relatively common on radiographic examinations, but significantly less often results in symptoms. According to review publications, up to 20% of women may have signs of nephroptosis on intravenous urography, but only a minority experience clinically significant manifestations. This emphasizes the importance of not only documenting the anatomical displacement but also assessing its functional consequences. [8]

The right kidney is predominantly affected, which is associated with differences in anatomical fixation and the length of the vascular pedicle. Symptom onset typically occurs between 20 and 40 years of age, when patients are physically active and may experience posture-related lower back or abdominal pain. [9]

Most cases are asymptomatic and are incidental findings on imaging performed for another reason. However, some patients exhibit functional impairment in the upright position, including decreased blood flow and signs of transient obstruction. This circumstance explains the historical controversy surrounding the clinical significance of the diagnosis. [10]

There are reports in the literature of associations between nephroptosis and other conditions, including fibromuscular dysplasia of the renal artery and orthostatic proteinuria, but these associations are not universal and require individual verification in functional studies. [11]

Table 2. Epidemiological landmarks

Indicator	Range
The proportion of individuals with nephroptosis on imaging	up to 20% of women
Symptomatic cases among those identified	noticeably less, units out of tens
The advantageous side	right
Typical age of clinical manifestation	20-40 years old
[12]

Reasons

The key cause is the relative insufficiency of the kidney's supporting structures: the fascial layers, the perirenal adipose tissue, and the anterior ligaments. When these structures are weak or their volume decreases, the kidney becomes more mobile and prone to downward displacement under the force of gravity during verticalization. Rapid weight loss can reduce the perirenal fat pad, worsening organ mobility. [13]

Pregnancy and childbirth can alter the tone of the abdominal wall and fascial support, which increases the risk of developing nephroptosis in predisposed individuals. Similar factors include trauma that damages supporting tissues and prolonged, significant physical exertion with increased intra-abdominal pressure. [14]

The role of connective tissue weakness is debated, including in hereditary collagenopathies. In these conditions, the supporting structures may be more extensible and less resilient to stress, theoretically increasing renal mobility. In each case, clinical evaluation and exclusion of other causes of pain are necessary. [15]

Nephroptosis is rarely described as a specific problem in kidney transplant recipients or after previous upper urinary tract interventions where the organ's anatomical fixation is altered. These situations involve specific clinical scenarios and require follow-up by a specialized team. [16]

Risk factors

Risk factors include low body weight and rapid weight loss, which reduces the volume of perirenal fat and weakens the renal bed. In lean young women, renal mobility is more likely to be clinically significant. [17]

Repeated pregnancies, childbirth, and conditions with prolonged elevated intra-abdominal pressure can also contribute to organ displacement. Jobs that involve regular heavy lifting and sports that place high stress on the core sometimes trigger the development of posture-related pain in predisposed patients. [18]

Congenital features of fixation, the length of the vascular pedicle, or the fascial apparatus may create predispositions to excessive mobility. Combined with external factors, this increases the likelihood of clinical manifestations. [19]

Finally, connective tissue diseases that reduce tissue strength may increase the risk of nephroptosis, although a direct cause-and-effect relationship needs to be confirmed in each individual case. [20]

Table 3. Risk factors for nephroptosis

Group of factors	Examples
Body type and nutrition	low body weight, sudden weight loss
Mechanical	pregnancy and the postpartum period, heavy lifting, prolonged standing
Anatomical	relative weakness of fascial fixation, length of vascular pedicle
Fabric	conditions with connective tissue weakness
[21]

Pathogenesis

In the upright position, the kidney displaces downward and can "kink" the ureter, leading to transient obstruction and dilation of the renal pelvis. In some patients, this is accompanied by pain, nausea, and episodes of acute urinary retention, known as a "Dietl crisis." In the supine position, the kink is straightened and symptoms subside. [22]

In addition to the mechanical component, displacement stretches the renal vascular pedicle, which can reduce blood flow and provoke ischemia. Doppler ultrasound imaging in the standing position reveals decreased perfusion compared to the supine position. These changes explain postural-related pain and possible fluctuations in blood pressure in susceptible patients. [23]

Long-term episodes of impaired urinary outflow increase the risk of upper urinary tract infections and stone formation, and repeated inflammatory reactions can lead to scarring and persistent functional decline. Therefore, if functional impairment occurs in the upright position, it is important to document and address it. [24]

The contribution of each mechanism is individual: in some patients, the pain component predominates without obvious obstruction, while in others, pronounced position-dependent dilation of the renal pelvis. Functional examination methods in two positions help to understand the leading pathogenetic pathway in a given individual. [25]

Symptoms

A typical symptom is a dull or aching pain in the side or lower chest, which intensifies with standing, walking, and physical activity and subsides when lying down. The pain sometimes radiates to the groin and is accompanied by nausea. The classic description of postural dependence helps suspect nephroptosis. [26]

Macrohematuria or microhematuria, decreased urine output accompanied by pain, and a sensation of a "sinking" mass in the abdomen are possible. If infection occurs, fever, painful urination, and increased urination frequency may occur. These symptoms require urgent evaluation and exclusion of other causes. [27]

Some patients experience periodic dilation of the renal pelvis upon standing, with rapid regression when lying down. In rare cases, crises with severe pain, nausea, and vomiting develop due to acute ureteral kinking. Between episodes, the patient may feel well. [28]

Some cases remain asymptomatic and are discovered incidentally. The clinical significance of such a finding is low unless functional tests in the standing position reveal obstruction and decreased perfusion. In these situations, observation and educational recommendations are usually sufficient. [29]

Table 4. Relationship of symptoms with body position

Sign	Standing	Lying down
Pain in the side	more often intensifies	decreases
Dilatation of the pelvis	may appear	regresses
Kidney perfusion	may decrease	is being restored
Nausea, urge to vomit	possible	are dying down
[30]

Classification, forms and stages

There is no strict universal staging scale for nephroptosis. In clinical practice, the criterion used is excessive renal mobility—a displacement of more than 5 cm or two vertebral heights when moving from a supine to a standing position—and the presence of functional impairment in the upright position is assessed. [31]

It is convenient to distinguish three clinical forms: asymptomatic renal mobility, symptomatic uncomplicated form with posture-dependent pain without objective obstruction, and symptomatic complicated form with documented outflow obstruction or decreased perfusion while standing. This operational approach helps plan examination and treatment. [32]

Rare variants are described separately: medial ptosis with medial organ displacement and combined conditions, for example, in the setting of fibromuscular dysplasia. These situations are considered on an individual basis in specialized centers. [33]

In the presence of hydronephrosis, clinicians use standard scales to assess its severity based on imaging data, but these scales relate to the degree of dilation and not to the staging of the nephroptosis itself. This is important for the interpretation of the results. [34]

Complications and consequences

Repeated episodes of ureteral kinking lead to transient or persistent obstruction and hydronephrosis. Long-term elevated pressure in the renal pelvis and collecting system poses a risk of infection, stone formation, and decreased renal function, especially if treatment is delayed. [35]

Impaired renal perfusion, especially with severe stretching of the vascular pedicle in the upright position, can provoke ischemia and episodes of pain. The role of renin-mediated arterial hypertension is discussed in some cases and should be assessed in conjunction with alternative causes. [36]

Upper urinary tract infections with obstruction are more common and require standard treatment, with attention to eliminating the underlying mechanical factor. Untreated obstruction increases the risk of stone formation and chronic inflammation. [37]

Surgical treatment, like any intervention, carries a risk of complications, including infection, hematoma, injury to adjacent structures, and incomplete elimination of mobility. However, with modern laparoscopic techniques, the incidence of serious complications is low, and the chances of lasting pain relief are high. [38]

When to see a doctor

Seek immediate medical attention if you experience severe flank pain with nausea or vomiting, fever, a marked decrease in urine output, or blood in the urine. These signs may indicate an acute ureteral kink or infection, which require urgent evaluation. [39]

Make an appointment with your doctor if position-related pain persists for several weeks, worsens when standing and improves when lying down, especially if you've recently lost weight. Your doctor will take your medical history, conduct an examination, and, if necessary, order tests in various body positions. [40]

Consult a urologist if you experience recurrent urinary tract infections, recurrent macrohematuria, or if previous studies have shown dilation of the renal pelvis while standing. In such cases, clarification of functional disorders and a discussion of treatment tactics are required. [41]

If you have underlying connective tissue conditions, are pregnant, or plan significant physical activity, discuss individualized prevention and monitoring measures with your healthcare provider. [42]

Diagnostics

Step 1. Collection of complaints and examination. The doctor clarifies the positional dependence of the pain, any triggering stress, and any episodes of hematuria and infection. During the examination, the patient is assessed for tenderness, and sometimes a displaced mass can be palpated. This stage determines the likelihood of a diagnosis and the choice of further tests. [43]

Step 2. Laboratory tests. A complete urinalysis is performed, including evaluation of red blood cells, white blood cells, and protein, as well as basic blood chemistry to assess kidney function. Laboratory changes are nonspecific and serve to exclude infection or bleeding. [44]

Step 3. Ultrasound examination in two positions. The key method is ultrasound examination in the supine and standing positions, supplemented by Doppler blood flow analysis. This allows one to visualize the magnitude of displacement, the appearance of pelvic dilation, and changes in perfusion during verticalization compared to the supine position. This method is often more sensitive to functional changes than radionuclide tests. [45]

Step 4. Radionuclide renography with diuretic stress in various positions. The examination, performed in a lying, sitting, or standing position, helps assess the division of function between the kidneys and the presence of urinary retention during vertical positioning. This test is particularly useful when the ultrasound image is ambiguous. [46]

Step 5. Intravenous urography in two positions. Historically, the standard method for confirming nephroptosis, demonstrating a displacement of more than 5 cm or two vertebral heights. It is now used less frequently, but remains informative when performed purposefully in the supine and standing positions. [47]

Step 6. Computed tomography or magnetic resonance imaging in complex cases. Conventional studies are performed in the supine position and may not reveal functional changes. They are used to exclude alternative causes of pain and anatomical abnormalities; if surgical planning is necessary, urographic protocols are used. [48]

Step 7. Invasive functional tests as indicated. In rare diagnostically challenging situations, a modified Whitaker test is used, assessing urodynamics in different positions. This method is invasive and is used sparingly in specialized centers. [49]

Table 5. Diagnostic algorithm

Stage	Target	What confirms
Ultrasound examination in the lying and standing positions with Doppler	displacement magnitude, perfusion, dilatation	anatomy and function during verticalization
Radionuclide renography in two positions	function and drainage	slowing down of withdrawal while standing
Intravenous urography in two positions	displacement visualization	criterion more than 5 cm or two vertebral heights
Computer and magnetic resonance imaging	exclusion of other reasons	concomitant pathology
Invasive tests	controversial cases	confirmation of obstruction
[50]

Differential diagnosis

Nephrolithiasis and acute colic are common alternatives for flank pain. Sudden onset, irradiation down the ureter, crystalluria, and typical CT findings support the diagnosis of a stone. With nephroptosis, pain is often postural-dependent and less closely related to stone movement. [51]

Hydronephrosis of other etiologies, including obstruction in the ureteropelvic junction, requires exclusion. Radionuclide and urographic tests, compared in the supine and standing positions, are helpful in this regard to demonstrate the precise positional nature of the outflow obstruction. [52]

Urinary tract infections and pyelonephritis are accompanied by fever, abnormal blood and urine tests, and typical signs of inflammation on imaging. In nephroptosis, infection occurs as a complication, so it is important to distinguish between primary infection and infection due to a mechanical factor. [53]

Musculoskeletal pain, gallbladder disease, and gynecological pathology are also included in the differential diagnosis. A proper history and targeted imaging can help avoid overdiagnosis of nephroptosis and focus on the causes that require priority treatment. [54]

Table 6. Differential diagnosis

State	What is in favor?	How to confirm
Nephrolithiasis	colicky pain, microhematuria	computed tomography without contrast
Ureteropelvic junction obstruction	persistent dilatation	urography, renography
Pyelonephritis	fever, leukocytosis	visualization of signs of inflammation
Mechanical pain	connection with movement, palpation	clinical tests
[55]

Treatment

Observation and education. If nephroptosis is detected incidentally and is not accompanied by functional impairment, dynamic observation, symptom monitoring, and education are sufficient. Maintaining a stable body weight, avoiding sudden weight loss, and selecting activities that do not provoke pain are recommended. [56]

Lifestyle modification and abdominal wall strengthening. For moderate symptoms, core and abdominal wall exercises, balanced physical activity, and the use of a support belt to relieve pressure during prolonged standing are helpful. The evidence base is limited, but these measures are safe and often reduce posture-related discomfort. [57]

Medication support for pain syndrome. Short courses of analgesics and anti-inflammatory drugs are used, taking into account their safety profile and the prevention of gastrointestinal and renal side effects. If infection occurs, antibacterial drugs are prescribed according to standard treatment guidelines for urinary tract infections. These medications relieve symptoms but do not stabilize the kidney. [58]

Treatment of concomitant infection and prevention of relapse. If pyelonephritis or cystitis is diagnosed, antimicrobial therapy is administered, while simultaneously assessing the need to address the mechanical cause. Prevention includes adequate fluid intake, prompt treatment of relapses, and control of factors contributing to urinary retention. [59]

Indications for surgery. Nephropexy is considered in cases of documented outflow obstruction or decreased perfusion in the upright position, recurrent infections associated with this condition, persistent severe postural-related pain that interferes with quality of life, and decreased function of the corresponding kidney, as determined by studies. The decision is made after a comprehensive assessment and exclusion of alternative causes of pain. [60]

Laparoscopic nephropexy. The current standard is fixation of the kidney to retroperitoneal structures with non-absorbable sutures using fascial strips or mesh materials. This method provides long-term pain relief in approximately 70-90% of selected patients and a faster recovery compared to open surgery. [61]

Robot-assisted nephropexy. This technology is used less frequently and primarily in centers with relevant experience. Publications demonstrate good fixation reproducibility and surgeon comfort in complex anatomy; however, the evidence base compared to laparoscopy is limited and relies on case series. [62]

Modified and minimally invasive techniques. Percutaneous methods for temporary kidney "suspension" with subsequent scar formation are described, as well as the use of modern fixation materials and adhesives. These approaches are considered on an individual basis and are typically part of specialized care. [63]

Open nephropexy. A historical method used today when laparoscopy is contraindicated or when combined reconstructions are necessary. Compared to minimally invasive methods, it is characterized by greater trauma and a longer recovery period. [64]

Postoperative follow-up and results. After nephropexy, pain regression, the absence of infections, the dynamics of renal function, and ultrasound imaging are monitored, preferably in two positions. Long-term follow-up confirms a sustained improvement in quality of life in most patients undergoing the procedure, provided they are properly selected. [65]

Table 7. Treatment options and expected effect

Approach	When appropriate	Expected result
Observation	asymptomatic mobility	security, control
Lifestyle and exercise	mild symptoms	reduction of discomfort
Medicines according to indications	pain, infection	relief of symptoms
Laparoscopic nephropexy	documented obstruction or persistent pain	long-term relief for most
Robot-assisted fixation	complex cases in examination centers	comparable with proper selection
[66]

Prevention

There is no specific prevention, but maintaining a stable body weight without sudden weight loss is important, as it helps preserve perirenal adipose tissue volume. If weight loss is necessary, this should be done gradually under specialist supervision. [67]

Rational physical activity with an emphasis on strengthening the abdominal wall and core muscles can reduce posture-related discomfort in symptom-prone patients. Exercise selection is individualized, avoiding pain provocation. [68]

Working with heavy loads requires ergonomics: avoid standing for long periods without breaks, use a support belt when lifting heavy objects, and plan to rest in a lying position if discomfort occurs. [69]

Prompt treatment of urinary tract infections and control of factors that impair outflow help prevent complications in patients with mobile kidneys. Frequent recurrences of infections require urological monitoring. [70]

Forecast

In most people, renal mobility is asymptomatic and does not affect life expectancy. The prognosis is favorable in the absence of functional impairment and complications; observation and a healthy lifestyle are sufficient. [71]

In symptomatic patients, the prognosis depends on the severity of the postural obstruction and the timely selection of treatment. With documented obstruction and properly performed nephropexy, the likelihood of sustained pain relief is high, and the risk of severe complications is low. [72]

Long-term untreated hydronephrosis with repeated kinks increases the risk of decreased function and infectious complications, which emphasizes the importance of early detection of functional disorders and their elimination. [73]

Regular contact with the doctor and monitoring of symptoms allow timely adjustment of the monitoring plan or transition to surgical treatment when indications arise. [74]

Table 8. Prognostic factors

Factor	Influence
Functional disorders while standing	worsen the prognosis without treatment
Frequency of infections	increases the risk of complications
Timeliness of nephropexy when indicated	improves outcome
Body weight stability	reduces the likelihood of progression
[75]

FAQ

Is this dangerous in itself or not? In most people, renal prolapse is a benign anatomical feature with no symptoms. The danger is not related to the "displacement," but to possible posture-related ureteral obstruction, infections, and hydronephrosis. In the absence of these, observation is sufficient. [76]

Is surgery possible? Yes, abdominal wall exercises, weight control, and ergonomic exercise can help with moderate symptoms. However, if functional impairment in the upright position is confirmed or there is persistent pain and recurrent infection, nephropexy is considered. [77]

Which surgery is better? In most cases, laparoscopic nephropexy is preferred: it's less invasive, has a faster recovery, and offers a higher chance of reducing pain. Robotic-assisted surgery is an option in experienced centers. The choice of method depends on the patient's anatomy and the associated needs. [78]

Why is the CT scan normal, but other tests don't? Because standard CT scans are performed in the supine position and don't show posture-related changes. The diagnosis is confirmed by examinations in the supine and standing positions—ultrasound with Doppler, renography, and urography. [79]

Can episodes of vomiting and pain recur? Yes, this is possible with temporary ureteral kinking while standing, a so-called Dietl's crisis. Such episodes require evaluation and, if the underlying mechanism is confirmed, a decision on treatment. [80]

Table 9. When observation is sufficient and when surgery is necessary

Scenario	Tactics
Incidental finding, no symptoms, no functional impairment	observation, lifestyle
Periodic pain without obstruction	non-drug measures, control
Documented obstruction when standing, recurrent infections, persistent pain	nephropexy
[81]